The mission of the Healthy Youth Development Prevention Research Center (UMN PRC) is to collaborate with health departments, related agencies and community partners to develop and disseminate actionable knowledge and practices that promote healthy development and health equity among all young people. Our specific aims, reflected in our unit-specific work plans, include the use of interdisciplinary research, training, community education, TA, capacity-building, strategic communications, and evaluations to build health, competence, and capacity throughout the second decade of life and beyond, and to build capacity in partners working with and on behalf of young people. Our long-term objectives focus on expansion of scientific knowledge and increased use of evidence-based public health programs that advances the national health agenda as reflected in Healthy People 2020's adolescent-focused goals (5 of 7 priority areas), promotes health equity as articulated in the National Prevention Strategy, and addresses CDC adolescent-related Winnable Battles (i.e., reproductive health). The UMN PRC core project, Partnering for Healthy Student Outcomes (PHSO) is a comparative study of the relative effectiveness of a school-based, social-emotional learning (SEL) prevention program for students attending culturally diverse, economically disadvantaged middle schools in the Minneapolis-St. Paul, MN metro area. Our primary research question is: Will a multi-year, school-based prevention program, infused with professional development (PD) aimed at increasing the capacity of middle school teacher teams to engage their students in learning, yield changes in middle school students' health risk behaviors and academic outcomes that exceed outcomes from a school-based student-focused prevention program alone? The research has two primary aims: Primary Aim 1: Conduct a pilot study to determine the feasibility and acceptability of a school-based, SEL+PD program (Positive Action plus teacher-team professional development and support) designed to reduce health risk behaviors (violence, bullying, substance use, sexual risk behaviors) and increase academic achievement among middle school students; and Primary Aim 2: Implement a SEL plus teacher-team professional development program and evaluate its effectiveness on student outcomes compared to a SEL program alone. We will evaluate the two conditions in a matched pairs, randomized trial involving approximately 840 students in 4 urban middle level schools across 3 school years.